Technical Field
The present invention generally relates to dual channel semiconductor devices and, more particularly, to the fabrication of such devices using a sacrificial liner that protects the channel during an oxide anneal.
Description of the Related Art
The fabrication of semiconductor devices frequently uses “shallow trench isolation” (STI) techniques to separate different devices and different device structures. STI commonly involves the formation of a trench between isolated regions and then filling that trench with a dielectric material, most commonly an oxide. Flowable oxides are used to produce STI structures that are free of seams, but a steam anneal is generally used to solidify the oxide material. If the channel structure of the device(s) is exposed to the steam anneal, this can oxidize the channel and damage or alter the properties of the device. In addition, in dual channel devices that have channels using different materials, the two channels may oxidize at different rates. A silicon nitride liner is sometimes used to prevent channel oxidation, but silicon nitride may induce a fixed charge in the device.